Lubricating system for power tools



1968 F. J. CONSOLI ETAL 3,367,447

LUBRICATING SYSTEM FOR POWER TOOLS Filed Oct. 1, 1965 172a 45 @a .42 45 I fig mews United States Patent Filed on. 1, 1965, Ser. No. 491,930 1 Claim. c1. 1s4 s9 ABSTRACT OF THE DISCLOSURE A power tool includes a crank arm and gearing for reciprocating a piston in a barrel forming part of the tool. The crank arm and gearing are contained in a chamber which is subjected alternately to high and low pressures because of movement of the piston. The lubricating system includes a reservoir mounted on the inside of a cover plate for the chamber, which reservoir has a bore mounting a sintered member which acts as a wick for the lubrieating oil. A one-way check valve is mounted in the cover plate and opens the reservoir and chamber to atmosphere during the creation of low pressure thereby to permit the lubricant to be drawn into the chamber for lubrication of the moving parts therein. During the development of high pressure, which is occasioned by return of the piston, the one-way check valve closes preventing escape of the oil.

The present invention relates to lubrication of a power tool of the type having a reciprocating element which alternately creates high and low pressures in the tool; more particularly, the invention relates to new and improved means adapting such a tool for self-lubrication.

An object of the present invention is to provide, in a power tool of the type described, an oil reservoir uniquely associated with vent means and oil absorbent means whereby oil is forced into contact with the moving parts of the tool in response to creation of low pressure in the tool during its operation.

Another object of the present invention is to provide an oil trap in association with the aforementioned elements thereby to maintain the oil absorbent member substantially immersed in oil during manipulation of the tool throughout various positions.

These and other objects and advantages of the invention will become apparent from the following specification disclosing a preferred embodiment of the invention which is illustrated in the accompanying drawing wherein:

FIG. 1 is a side elevational view of a power tool in which the present invention is incorporated, which tool is shown with a wall portion thereof broken away for illustration of the present invention;

FIG. 2 is an enlarged view taken along line 22 of FIG. 1 and showing the reservoir supporting plate partially broken away for better illustration of the reservoir and the oil absorbent member; and

FIG. 3 is a section taken along line 3-3 of FIG. 2.

By way of introduction, the present invention is adapted for use in a power tool of the type having a housing chamber enclosing movable parts, such as a crank arm and a piston rod, connected with a piston for reciprocating the same in a cylinder which opens into the chamber. The present invention includes an oil reservoir mounted in the tool housing adjoining the chamber, which reservoir supports an oil absorbent member with a portion thereof in the reservoir for being immersed in oil therein and with another portion of the oil absorbent member exposed to the chamber. A vent opens the reservoir to atmosphere and through the medium of the oil absorbent member also opens or communicates the chamber with atmosphere. When low pressure is created in the chamber upon movement of the piston in a direction away from the chamber,

Patented Feb. 6, 1968 oil is forced by atmospheric pressure into the chamber for lubricating the moving parts therein.

Now referring to the drawing, the present invention is shown incorporated in the rotary hammer forming the subject matter of Etzkorn et al. Patent 3,161,242, assigned to the assignee of the present invention. It will be understood that the present invention is shown in association with this Etzkorn et al. tool for purposes of illustration only; the present invention has equal utility in other forms of power tools which include a reciprocating member, such as a piston, which alternately creates high and low pressures in a chamber enclosing mechanical parts which actuate the piston.

Briefly and by way of background, the Etzkorn et al. tool, which is covered in the aforementioned patent and therefor of itself forms no part of the present invention, includes a housing 11) enclosing a suitable electric motor (not shown). The tool also includes the usual handle 11 which supports a trigger 12 for activating the tool motor. The electric motor drives an output gear 14 which meshes with another gear 15 for driving the latter. Gear 15 is suitably journaled in the tool and is connected with a crank arm 16 for rotating the same. Crank arm 16 is pivotally connected with a piston rod 17, which piston rod is pivotally connected with a piston 18 for reciprocating the same in a cylinder 21 Cylinder 20 contains a freely slidable piston or striker 21 which is pneumatically reciprocated by action of piston 18 for impacting engagement with the inner end of a working tool member 22.

Gear 15 has a smaller in diameter gear 23 associated therewith; this gear meshes with a larger diameter gear 24. This gear drives a bevel gear 25 meshing at a right angle with another bevel gear 26. Bevel gear 26 is connected with cylinder 20 for rotating the latter, cylinder 20 being suitably journaled within the tool housing. Cylinder 20 serves to rotate the working tool member 22 as the latter is being struck or impacted by the striker. It should be apparent that working tool member 22 is simultaneously rotated and hammered upon operation of the rotaryharnmer tool.

The tool contains an upper housing portion 27 which defines a chamber 28 containing crank arm 16 and piston rod 17. Cylinder 20 opens into this chamber 28. For a more detailed explanation of the tool shown for purposes of illustration, reference should be had to the aforementioned Etzkorn et al. patent.

Looking now particularly to FIGS. 2 and 3, the present invention will be seen to include a plate 30 which is adapted to be secured to tool housing portion 27 for closing chamber 28. Plate 30 may be removably secured to housing 27 by a plurality of fasteners, one of said fasteners being shown in FIG. 2 and identified by reference character 31. Connected to the underside of plate 30 is a reservoir 32 defined by a bottom wall 33, side walls 34, 35 and front and rear walls 36, 37, respectively. The reservoir may be secured to the underside of plate 30 by a number of fasteners (one fastener is shown in FIG. 2 and identified by numeral 38) received in threaded bores 39 formed in the reservoir. The reservoir includes a raised bottom portion 33a at the front end thereof. The reservoir also includes an upright, semi-circular wall 40 integral with raised bottom portion 33a. As noted in FIG. 2, the ends 40a of the wall do not contact front wall 36 of the reservoir. As will be explained hereinbelow, wall 40 defines a trap which comes into play when the tool illustrated is used for overhead operation.

Plate 31) includes an aperture 30a in which an internally threaded bushing or sleeve 41 is fixedly mounted. A removable cap 42 is threadingly engaged in sleeve 41. Removal of cap 42 permits reservoir 32 to be filled with a quantity of oil. Cap 42 contains vent means for venting reservoir 32 to atmosphere when the pressure therein is 3 less than atmospheric; this vent means will now be described.

The cap 42 includes a central stepped bore 42a in which a one way check valve 43 is mounted. This valve may be a duckbill check valve of the type manufactured by Vernay Laboratories, Inc. It will be understood that this check valve permits air to be admitted into reservoir 32 from atmosphere but prevents an opposite flow of air. The check valve 43 is sealed in the central bore in cap 42 by an O-ring 44. Seated on top of the O-ring is an air filter or screen 45, which screen is held in place by a split ring 46 received within an annular groove formed in bore 42a.

The forward end of the reservoir includes a through bore 48 in bottom portion 33a. This bore receives a reduced in diameter lower portion 49a of an oil absorbent member 49. A sleeve-like filter 50 surrounds the upper or enlarged portion 49b of the oil absorbent member.

In a preferred embodiment of the invention, oil absorbent member 49 is formed of sintered or porous bronze metal and sleeve 50 is formed of a felt material. Filter 50 is of course not essential but merely preferred. Oil absorbent member 49 may also be formed of a felt or wicklike material for absorbing oil in the reservoir 32. At any rate, the member 49 must be formed of a material having interconnected openings or cells for absorbing oil and causing passage of the same from the reservoir to chamber 23 in which portion 49a of member 29 is disposed. Since member 49 is absorbent and formed of porous material, this member in effect communicates chamber 28 with reservoir 32, which reservoir is communicated with atmosphere by check valve 43 upon opening of the latter.

The operation of the lubrication system of this invention is as follows:

Reservoir 32 is substantially filled with a supply of oil. The oil in the reservoir flows around the ends 40a of wall 40 (when the rotary-hammer is held in a position other than a position for overhead operation), passes through filter 50 and, after a relatively short period of time, becomes absorbed by member 49 throughout the entire length thereof. As the power tool is operated, piston 18 is reciprocated in cylinder which opens into chamber 28. Accordingly, piston 18 alternately forms high and low pressures in chamber 28.

When low pressure is formed in the chamber 28, i.e., as piston 18 is advanced forwardly, a corresponding low pressure is formed in reservoir 32 (since the chamber 28 and the reservoir are in communication via member 49) and therefore the check valve 43 opens to atmosphere.

Accordingly, atmospheric pressure then forces oil in the member 49 into chamber 28 for lubricating the moving parts therein, viz, piston rod 17, crank arm 16 and the drive means therefor. Upon return of the piston, check valve 43 is closed thereby preventing escape to atmosphere of any oil in the reservoir. It should be apparent that the present invention adapts the power tool to lubricate itself during its operation.

Should the power tool be held substantially vertical as for overhead operation, for example, a quantity of oil will be trapped within wall 40 in the reservoir thereby maintaining portion 49b of the oil absorbent member substantially immersed for lubricatin the tool during overhead operation. Should it be necessary to operate the tool for an extended period of time in overhead operation, the tool may be periodically returned to a horizontal position in which case additional oil in the reservoir will be allowed to flow into the area of the reservoir within wall 40. Actually, fatique by the operator of the tool prevents overhead operation for such a length of time that the oil absorbent member 49 would become dry. When the operator returns the tool to a level or downwardly inclined position for resting his arms, additional oil will be allowed to fiow to the area of the reservoir defined by the curved wall 40. The reservoir itself may be readily replenished with a supply of oil by removing the cap 42.

The reservoir 32 is adapted to contain a suificient quantity of oil to permit operation of the tool for a considerable period of time without replenishing oil in the reservoir. The present invention obviates known lubrication systems for power tools which generally include lubrication ports or fittings requiring the admission of oil at frequent intervals during operation of the tool.

While the invention has been shown in but only one form, it will be obvious to those skilled in the art that it is not to be so limited. On the contrary, the invention is susceptible of various forms and modifications without departing from the spirit and scope of the appended claim.

We claim:

1. In a tool of the type including a housing having a cavity containing relatively movable, mechanically interconnected parts for reciprocating a piston in a cylinder which opens into said cavity, the improvement comprising, a hcusing plate secured to said housing and defining, with said cavity, a closed chamber, an oil reservoir mounted on the inside of said plate and thereby being disposed in said chamber, said plate including a normally closed one way check valve for venting said reservoir to atmosphere upon opening of said valve, which valve opens in response to a reduction in pressure in said reservoir, a member mounted with a portion thereof in said reservoir for being immersed in oil contained in the latter and with another portion thereof exposed to said chamber, which member has interconnected openings for absorbing oil and for communicating said chamber with said reservoir, whereby upon creation of low pressure in said chamber during movement of said piston in one direction said valve is opened and oil in said member is forced into the chamber for lubricating said parts therein, movement of said piston in the other direction serving to close said valve and thereby prevent escape of oil from said reservoir.

References Cited UNITED STATES PATENTS 2,011,491 8/1935 Kucera 1846 2,150,619 3/1939 Bonis 184-6 3,213,966 10/1965 Veres et al. 184-55 LAVERNE D. GEIGER, Primary Examiner. E. J. EARLS, Assistant Examiner. 

